code: def test_untransform_observation_features_HSS(self) -> None:
      # Test transformation in one subtree of HSS.
      with patch.object(
          self.t_hss.search_space,
          "cast_observation_features",
          wraps=self.t_hss.search_space.cast_observation_features,  # pyre-ignore
      ) as mock_cast_obsf:
          obs_feats = self.t_hss.untransform_observation_features(
              observation_features=[self.obs_feats_hss]
          )
          mock_cast_obsf.assert_called_once()
  
      self.assertEqual(len(obs_feats), 1)
      obsf = obs_feats[0]
      self.assertEqual(
          obsf.parameters,
          {
              "model": "Linear",
              "learning_rate": 0.01,
              "l2_reg_weight": 0.0001,
          },
      )
      self.assertEqual(
          # pyre-fixme[16]: Optional type has no attribute `get`.
          obsf.metadata.get(Keys.FULL_PARAMETERIZATION),
          self.obs_feats_hss.parameters,
      )
  
      # Test transformation in other subtree of HSS.
      obs_feats_2 = self.t_hss.untransform_observation_features(
          observation_features=[self.obs_feats_hss_2]
      )
      self.assertEqual(len(obs_feats_2), 1)
      obsf = obs_feats_2[0]
      self.assertEqual(
          obsf.parameters,
          {
              "model": "XGBoost",
              "num_boost_rounds": 12,
          },
      )
      self.assertEqual(
          obsf.metadata.get(Keys.FULL_PARAMETERIZATION),
          self.obs_feats_hss_2.parameters,
      )
  
file_path: Ax/ax/modelbridge/transforms/tests/test_cast_transform.py
imports: from copy import deepcopy
  from unittest.mock import patch
  from ax.core.observation import ObservationFeatures
  from ax.core.parameter import ChoiceParameter, FixedParameter, ParameterType, RangeParameter
  from ax.core.search_space import HierarchicalSearchSpace, SearchSpace
  from ax.modelbridge.transforms.cast import Cast
  from ax.utils.common.constants import Keys
  from ax.utils.common.testutils import TestCase
  from ax.utils.testing.core_stubs import get_hierarchical_search_space
label_desc: Use image node_id 7 for calling the CastTransformTest obj's underlying member method code with example usage: obj.test_untransform_observation_features_HSS() without return types